1. Field of the Invention
The present invention relates to a protective structure for a flat cable, and more particularly to a structure for protecting and guiding a flat cable connected between a traveling module and a cover arranged in an image scanning device.
2. Description of the Prior Art
In various kinds of optical devices or electric appliances (such as image scanner, photo copier, test instrument, etc.), there is often equipped with traveling modules therein. For example, as shown in FIG. 1, it is a perspective view of a conventional image scanning device, showing that a focusing lens 2, a protective cover 3, a pair of corresponding guide rods 4a, 4b, and two movable traveling modules 5a, 5b are arranged in the housing 1 of the conventional optical image scanner.
The guide rods 4a, 4b serve as a guiding mechanism for guiding two traveling modules 5a, 5b. The first traveling module 5a carries a light tube as a light source for the image scanning device, while the second traveling module 5b carries a set of reflection mirrors for reflecting the light projected from the light source.
During scanning, a document to be scanned is placed on a document positioning plate of the scanner. It is known that the document positioning plate is a plane surface made of for example glass or other light transmittable, substantially rigid material, for supporting a document to be scanned. The light tube of the first traveling module 5a projects a light toward the document and then the light is reflected by the reflection mirror mounted in the second traveling module 5b.
The first and second traveling modules 5a, 5b are arranged to achieve a necessary scanning optical path during scanning. Typically, the first and second traveling modules 5a, 5b may be moved by a conventional driving motor via a transmission rope (not shown). In general, the ratio of the speed of the first traveling module 5a to the speed of the second traveling module 5b is 2:1.
In general, a flat cable 6 is connected between the traveling module 5a and the protective cover 3. The protective cover 3 contains therein a circuit board and relevant electronic components. One end of the flat cable 6 is connected to a connector socket 61 of the traveling module 5a, and the other end of the flat cable 6 is extended into the protective cover 3 via an opening 31 formed on the protective cover 3. So, the traveling module 5a can via the flat cable 6 obtains necessary controlling signals and electric power source from the electronic components arranged in the protective cover 3.
Generally, in order to minimize the length of the flat cable, the opening 31 on the protective cover 3 is located at a substantially middle section of the scanner.
Due to the material of the flat cable 6 itself, in the using regulation, the minimum curvature radius and the tolerable number of bending time of the flat cable 6 are limited. Under the connection structure of the conventional flat cable described above, since the traveling module 5a needs to frequently move left and right, the flat cable 6 will be repeatedly bent during scanning. In the case of excess bending angle, the flat cable 6 may be broken or damaged.
Moreover, the width of the existing flat cable is narrower and narrower (the number of pins is reduced) with longer length (such as used in scanning of A3 size document). Therefore, during the movement of the traveling modules, the flat cable is likely to curve and touch other components (such as the bottom surface of the document positioning plate of the scanner). In addition, the flat cable may swing left and right during movement of the traveling modules. These all lead to lowered reliability and shortened using life of the scanner.